Yeah velocities are everything as well as timing. Don't use 127 all the time it just sounds like an RnB beat. I usually stay within 105-125 for the hard hits. I even use velocities down to around 40...

There is no battle unless you create it. But you are right that a mediocre technique can limit your expression. In fact, this is one reason why I like singing for example...it is the only instrument...

No you won't run out of note combinations but yes, music can be a bit limiting when you need to express yourself. You may only express very general moods: sad, happy, uplifting, dark etc. That's why...